Ink, ink cartridge, and image-recording method

Abstract

An ink contains a pigment dispersed with polymer, a surfactant, a water-soluble organic solvent, and water. The mass ratio of a content of the pigment to a content of the polymer in the ink is more than 3. The surfactant includes a fluorinated surfactant which is represented by Formula (1) and which has an HLB of 11 or less as determined by a Griffin method. The water-soluble organic solvent includes at least one selected from specific Group A. The total content of the water-soluble organic solvents of the Group-A in the ink is larger than the total content of water-soluble organic solvents other than the water-soluble organic solvents of Group A in the ink.

What is claimed is:  
     
       1. An ink comprising:
 a pigment dispersed with polymer; 
 a surfactant; 
 a water-soluble organic solvent; 
 at least one additive selected from Group B consisting of tetritol, pentitol, hexitol, heptitol, octitol, and polyethylene glycol with a weight-average molecular weight of more than 10,000 and 100,000 or less; and 
 water, 
 wherein the mass ratio of a content of the pigment to a content of the polymer is more than 3; 
 wherein the surfactant includes a fluorinated surfactant having an HLB value of 11 or less determined by a Griffin method and represented by Formula (1): R 1 (CR 2 R 3 ) n CH 2 CH 2 (OCH 2 CH 2 ) m OH 
 wherein, R 1  represents a fluorine atom or a hydrogen atom; R 2  and R 3  each independently represent a fluorine atom or a hydrogen atom, provided that at least one of R 2  and R 3  represents fluorine atom; n represents a number of 1 or more and 30 or less; and m represents a number of 1 or more and 60 or less; 
 wherein the water-soluble organic solvent includes at least one water-soluble organic solvent selected from Group A consisting of glycerin, ethylene glycol, diethylene glycol, polyethylene glycol with a weight-average molecular weight of 10,000 or less, 1,3-propanediol, 1,4-butanediol, and diglycerol; and 
 wherein the total content of the water-soluble organic solvents of the Group-A in the ink is larger than the total content of water-soluble organic solvents other than the water-soluble organic solvents of Group A in the ink. 
 
     
     
       2. The ink according to  claim 1 , wherein the mass ratio of the total content of the water-soluble organic solvents of the Group-A to the total content of water-soluble organic solvents other than the water-soluble organic solvents of Group A, on the basis of the total mass of the ink, is 3 or more. 
     
     
       3. The ink according to  claim 1 , wherein the content of a surfactant other than the fluorinated surfactant is 0.1% by mass or less on the basis of the total mass of the ink. 
     
     
       4. An ink cartridge comprising an ink storage portion for storing ink, wherein the ink stored in the ink storage portion is the ink according to  claim 1 . 
     
     
       5. An image-recording method comprising:
 a conveying step of conveying a recording medium; and 
 an ink-applying step of applying ink to the recording medium, 
 wherein the ink is the ink according to  claim 1 . 
 
     
     
       6. The image-recording method according to  claim 5 , further comprising a heating step of heating the recording medium provided with the ink subsequently to the ink-applying step such that the surface temperature of the recording medium is 70° C. or more. 
     
     
       7. The image-recording method according to  claim 5 , wherein the ink is applied to the recording medium with a tension of 20 N/m or more in the ink-applying step. 
     
     
       8. The image-recording method according to  claim 5 , wherein the conveying speed of the recording medium in the conveying step is 50 m/minute or more. 
     
     
       9. The ink according to  claim 1 , wherein the polymer is synthesized from at least two of monomers, one of which is acrylic acid or methacrylic acid.